Network Working Group Y. Luo
Internet-Draft L. Ou
Intended status: Informational China Telcom Co., Ltd.
Expires: September 6, 2018 X. Huang
Tencent
S. Zhuang
Z. Li
Huawei
March 5, 2018
Traffic Steering Based on BGP Controller
draft-luo-grow-bgp-controller-based-ts-00
Abstract
Due to the dramatically increased network traffic and the desire of
differentiated services, it is essential for operators to provide the
traffic steering service under limited network resources and maximize
their benefits at the same time. The traditional method for traffic
steering depends on static configuration which is time consuming and
error-prone. As development of SDN, the controller is introduced for
traffic steering with the global view of network topology and route
information. This document describes typical use cases for traffic
steering services and proposes the traffic steering solution based on
BGP controller.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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material or to cite them other than as "work in progress."
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This Internet-Draft will expire on September 6, 2018.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Network Topology Collection . . . . . . . . . . . . . . . 4
3.2. Route Information Collection . . . . . . . . . . . . . . 4
3.3. Route Control . . . . . . . . . . . . . . . . . . . . . . 4
4. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Business-oriented Steering . . . . . . . . . . . . . . . 5
4.1.1. An Example of Preferential Users . . . . . . . . . . 5
4.1.2. An Example of Preferential Services . . . . . . . . . 6
4.2. Traffic Congestion Mitigation . . . . . . . . . . . . . . 6
4.2.1. An Example of Congestion Mitigation in Core . . . . . 7
4.2.2. An Example of Congestion Mitigation among ISPs . . . 7
4.2.3. An Example of Congestion Mitigation at International
Edge . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Transporting data to their users through the network is a fundamental
service that can benefit both providers and consumers. Since data/
information transport is playing a key role nowadays, operators have
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to face this increasing challenge through satisfying services with
differentiated criterias, such as latency, throughput, reliability
and even user-defined constraints. Moreover, the internet traffic
changes rapidly and is hard to be predicted, so there is chance that
the network will be congested. However, the network capacity
expansion takes time and could not meet the differentiated service
requirement or solve the congestion problem in time. As a result it
is nessesary to introduce traffic steering techniques into the
network. The traditional method for traffic steering depends on
static configuration which is time consuming and error-prone. As
development of SDN, the controller is introduced for traffic steering
with the global view of network topology and route information. This
document describes typical use cases for traffic steering services
and proposes the traffic steering solution based on BGP controller.
2. Terminology
o QoS: Quality of Service
o ISP: Internet Service Provider
o MAN: Metropolitan Area Network
o OTT: Over the Top
o OTTSP: Over the Top Service Provider, or Content Operator
o AR: Access Router
3. Architecture
The following figure shows the solution of traffic steering through
BGP controller.
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+-------------------+
| |
| BGP |
|----------| Controller |--------|
| | | |
| +-------------------+ |
| ^ | ^ |
Route Control / | \ Route Control
| / | \ |
| Topo/Route | Topo/Route |
| Info Collection | Info Collection |
| / | \ |
\|/ / | \ \|/
+--------+ +--------+ +--------+
| CLIENT | | CLIENT | | CLIENT |
| | ...... | | ...... | |
| (PE) | | (P) | | (PE) |
| | | | | |
+--------+ +--------+ +--------+
Figure 6 Traffic Steering through BGP Controller
3.1. Network Topology Collection
In order for traffic steering the BGP Controller must get the
topology of the whole network. [RFC7752] can be used to collect the
topology information of the network domain and
[I-D.ietf-idr-bgpls-segment-routing-epe] can be used to collect the
inter-domain topology information.
3.2. Route Information Collection
In order to steering traffic in and/or out the network, the BGP
controller must learn the existing BGP route information in the
network. There are several ways to learn the BGP route information
from the network:
1. The BGP controller can work as the route reflector so that it can
directly learn the BGP route from the client.
2. The BGP controller can also learn the BGP route through BGP
Mornitoring Protocol [RFC7854].
3.3. Route Control
Based on the servie requirement BGP controller can calculate the
traffice steering policy for the specific BGP route. The traffice
steering policy should be advertised from the BGP controller along
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with the route information to the clients in the network to take
effect. BGP, PCE and Netconf can be used for the advertisement.
4. Use Cases
4.1. Business-oriented Steering
It is a reasonable commercial way to provide multiple paths to the
same destination with differentiated experiences to preferential
users/services. This is an efficient approach to maximize providers'
network resources as well as their profit and offer more choices to
network users.
4.1.1. An Example of Preferential Users
+----------+
| HongKong |
--+----------+--
--- | ---
--- | ---
-- | --
+----------+ | +----------+
|Singapore | | | LA |
+----------+ | +----------+
-- |Path1 --
--- | ---
Path2 --- | --- Path3
--+----------+--
| Sydney |
+----------+
|
|
+-----------+-----------+
| | |
+-------+ +-------+ +-------+
|Silver | |Gold | |Bronze |
|Users | |Users | |Users |
+-------+ +-------+ +-------+
Figure 1 Differentiated Path Selection for Different User
In the above ISP network, there are three kinds of users in Sydney,
saying Gold, Silver and Bronze, and they wish to visit website
located in HongKong. The ISP provides three different paths with
different experiences according to users' priority. The Gold Users
may use Path1 with less latency and loss. The Silver Users may use
the Path2 through Singapore with less latency but maybe some
congestion there. The Bronze Users may use Path3 through LA with
some latency and loss.
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4.1.2. An Example of Preferential Services
* *
City A * City B * City C
* *
* +-----+ *
* |Users| *
* +-----+ *
* | *
+-----------+-----------+
| * | * |
+-----+ * +-----+ * +-----+
| R11 |-----| R12 |-----| R13 |
+-----+ * +-----+ * +-----+ ISP
| * | * |
*****|***********|***********|*********
| * | * |
| * | * | OTT
+-----+ * +-----+ * +-----+
| R21 |-----| R22 |-----| R23 |
+-----+ * +-----+ * +-----+
| * | * |
+-----------+-----------+
* | *
* +-----+ * +-------+
* | AR |--------|Content|
* +-----+ * |Server |
+-------+
Figure 2 Differentiated Path Selection for Different Services
As depicted above, the OTTSP has 3 exits with one ISP, which are
located in City A, City B and City C. The content is obtained from
Content Server and send to the exits through AR. an OTTSP may make
its steering strategy based on different services. For example, the
OTTSP in the graph above may choose exit R21 for video service and
exit R22 for web service, which REQUIREs a mechanism/system exists to
identify different services from traffic flow.
4.2. Traffic Congestion Mitigation
It is a persistent goal for providers to increase the utilization
ratio of their current network resources, and to mitigate the traffic
congestion. Traffic congestion is possible to happen anywhere in the
ISP network(MAN, IDC, core and the links between them), because
internet traffic is hard to predict. For example, there might be
some local online events that the network operators didn't know
beforehead, or some sudden attack just happened. Even for the big
events that can be predicted, such as annual online discount of
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e-commerce company, or IOS update of Apple Inc, we could not
guarantee there is no congestion. Since the network capacity
expansion is usually an annual operation, there could be delay on any
links of the engineering. As a result, the temporary traffic
steering is always needed. The same thing happens to the OTT
networks as well.
It should be noted that, the traffic steering is absolutely not a
global behavior. It just acts on part of the network, and it's
temporary.
4.2.1. An Example of Congestion Mitigation in Core
Core
+----------+
| Core A |
+------+ --+----------+-- +------+
|MAN C1|-+ --- --- +-|MAN D1|
+------+ | --- --- | +------+
| -- -- |
| +----------+ +----------+ |
+-| Core C | | Core D |-+
| +----------+ +----------+ |
| -- -- |
+------+ | --- --- | +------+
|MAN C2|-+ --- --- +-|MAN D2|
+------+ --+----------+-- +------+
| Core B |
+----------+
Figure 3 An Example of Congestion Mitigation in Core
As depicted above, traffic from MAN C1 to MAN D2 follows the path
Core C->Core B->Core D as the primary path, but somehow the load
ratio becomes too much. It is reasonable to transfer some traffic
load to less utilized path Core C->Core A->Core D when the primary
path has congestion.
4.2.2. An Example of Congestion Mitigation among ISPs
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* *
City A * City B * City C
* *
+-------+ * +-------+ * +-------+
|IXP A1 |----|IXP B1|---|IXP C1 |
+-------+ * +-------+ * +-------+ ISP 1
| * | * | |
*******|*************|*********|**|**********
| +----------|---------+ |
| | * | * | ISP 2
| | * | * |
+------+ * +------+ * +------+
|IXP A2|----|IXP B2|----|IXP C2|
+------+ * +------+ * +------+
| * | * |
| * | * |
+-------+ * +-------+ * +-------+
|Core A |----|Core B |---|Core C |
+-------+ * +-------+ * +-------+
Figure 4 An Example of Congestion Mitigation among ISPs
As depicted above, ISP1 and ISP2 are interconnect by 3 exits which
are located in 3 cities respectively. The links between ISP1 and
ISP2 in the same city are called local links, and the rest are long
distance links. Traffic from IXP C1 to Core A in ISP 2 usually
passes through link IXP C1->IXP A2->Core A. This is a long distant
route, directly connecting city C and city A. Part of traffic could
be transferred to link IXP C1->IXP B1->IXP A1->IXP A2->Core A when
the primary route congest.
4.2.3. An Example of Congestion Mitigation at International Edge
An ISP usually interconnects with more than 2 transit networks at the
international edge, so it is quite common that multiple paths may
exist for the same foreign destination. Usually those paths with
better QoS properties such as latency, loss, jitter and etc are often
preferred. Since these properties keep changing from time to time,
the decision of path selection has to be made dynamically.
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********************************
* *
* AS C1 *
* * AS Y1
* *
* +---+ +---+ * +-----------+
* /| B |---------| C |-----| Transit A | AS Z1
* / +---+\ +---+ * +-----------+--
* / | \\ // | * -- +-------------+
*+---+/ | \\// | * --| |
*| A | | //\ | * |Destination H|
*+---+\ | // \\ | * --| |
* \ | / \ | * -- +-------------+
* \ +---+ +---+ * +-----------+--
* \| D |---------| E |-----| Transit B |
* +---+ +---+ * +-----------+
* *
* IP Core * AS X1
* *
********************************
Figure 5 An Example of Congestion Mitigation at International Edge
As depicted above, the traffic to the foreign destination H from IP
core network (AS C1) has two choices on transit network, saying
Transit A and Transit B. Under normal conditions, Transit B is the
primary choice, but Transit A will be preferred when the QoS of
Transit B gets worse. As a result, the same traffic will go through
Transit A instead.
5. Contributors
Nan Wu
Huawei
Email: eric.wu@huawei.com
6. IANA Considerations
This document has no request to IANA.
7. Security Considerations
This document has no security issue introduced.
8. Acknowledgements
TBD.
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9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
9.2. Informative References
[I-D.ietf-idr-bgpls-segment-routing-epe]
Previdi, S., Filsfils, C., Patel, K., Ray, S., and J.
Dong, "BGP-LS extensions for Segment Routing BGP Egress
Peer Engineering", draft-ietf-idr-bgpls-segment-routing-
epe-14 (work in progress), December 2017.
[I-D.li-idr-flowspec-rpd]
Li, Z., Ou, L., Luo, Y., Lu, S., Zhuang, S., and N. Wu,
"BGP FlowSpec Extensions for Routing Policy Distribution
(RPD)", draft-li-idr-flowspec-rpd-02 (work in progress),
June 2016.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
Monitoring Protocol (BMP)", RFC 7854,
DOI 10.17487/RFC7854, June 2016,
<https://www.rfc-editor.org/info/rfc7854>.
Authors' Addresses
Yujia Luo
China Telcom Co., Ltd.
109 West Zhongshan Ave,Tianhe District
Guangzhou 510630
China
Email: luoyuj@gsta.com
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Liang Ou
China Telcom Co., Ltd.
109 West Zhongshan Ave,Tianhe District
Guangzhou 510630
China
Email: oul@gsta.com
Xiang Huang
Tencent
Email: terranhuang@tencent.com
Shunwan Zhuang
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: zhuangshunwan@huawei.com
Zhenbin Li
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
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